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rocky shore

Sea slug Onchidium sp. Family Onchidiidae

Sea slugs are sometimes seen on algae-covered rocks, usually when its cool. Sea slugs often blend perfectly with the rocks in both colour and texture! Bits of sand and sediments that get stuck on their skin adds to the camouflage. They may also be found on algae covered roots of mangrove trees. At high tide, they burrow into mud or sand, trapping an air bubble to breathe from. The guides affectionately call these amusing slugs 'onchs'. Shell-less but not helpless: Sea slugs are gastropods that don't have a shell as adults. Instead, they have tough skin to reduce water loss, and modified gills on their backsides to breathe air. These slugs belong to the same group as land snails. Slug Food: Sea slugs graze on algae and lichen on rocks at low tide, they are more commonly seen on cool mornings or evenings. Sea Slug Babies: Sea slugs are hermaphrodites, each slug having both male and female reproductive organs.

quick facts
0.8-6cm, sometimes seen on the rocky shore

Classification:
Class Gastropoda
Phylum Mollusca

See also ...
Molluscs in general
Gastropods in general

Links
Marine Pulmonate Slugs on the Sea Slug Forum website: a brief intro to Onchidium with lots of emails queries and photos and Bill Rudman's responses to them.
Slug Info on The House of Slime website: brief fact sheet with labelled diagram of a typical slug (based on a land slug)

Other references

Ng, Peter K. L. & N. Sivasothi, 1999. A Guide to the Mangroves of Singapore II (Animal Diversity). Singapore Science Centre. 168 pp. online version
Tan, Leo W. H. & Ng, Peter K. L., 1988. A Guide to Seashore Life. The Singapore Science Centre, Singapore. 160 pp. online version

a companion website to the chek jawa guidebook website©ria tan 2003 www.wildsingapore.com

a companion website to the chek jawa guidebook
website©ria tan 2003 www.wildsingapore.com